Mama Garden was wonderful place to stay. It was very clean and organized. The cottage is cozy -- I think it would be hard to fit more than 3 adults. It is also tucked away and opens out to a nice courtyard. The location is fairly central, although on the wrong side of the river if you're interested in going out at night to Sukhumvit or RCA. It is quite close to the river (5 min walk) and the local ferry, which runs quite often and is very cheap (4.5 Baht).
Mong was a wonderful host. Her breakfasts were a highlight and made the stay special. She is very helpful and will give you some tips upon arrival on how to get around (like how to use the ferry and which markets to visit). She was also very quick to respond to my questions.
One thing to be aware of is that there were mosquitos in the courtyard, so bring bug spray or mosquito bracelets if you plan to stay outside for long periods.